Audio encoder, audio decoder, method for encoding an audio information, method for decoding an audio information and computer program using a detection of a group of previously-decoded spectral values

Abstract

An audio decoder for providing a decoded audio information includes a arithmetic decoder for providing a plurality of decoded spectral values on the basis of an arithmetically-encoded representation of the spectral values and a frequency-domain-to-time-domain converter for providing a time-domain audio representation using the decoded spectral values. The arithmetic decoder is configured to select a mapping rule describing a mapping of a code value onto a symbol code in dependence on a context state. The arithmetic decoder is configured to determine or modify the current context state in dependence on a plurality of previously-decoded spectral values. The arithmetic decoder is configured to detect a group of a plurality of previously-decoded spectral values, which fulfill, individually or taken together, a predetermined condition regarding their magnitudes, and to determine the current context state in dependence on a result of the detection.

An audio encoder uses similar principles.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of copending International Application No. PCT / EP2010 / 065725, filed Oct. 19, 2010, which is incorporated herein by reference in its entirety, and additionally claims priority from U.S. Application No. 61 / 253,459, filed Oct. 20, 2009, which is also incorporated herein by reference in its entirety.[0002]Embodiments according to the invention are related to an audio decoder for providing a decoded audio information on the basis of an encoded audio information, an audio encoder for providing an encoded audio information on the basis of an input audio information, a method for providing a decoded audio information on the basis of an encoded audio information, a method for providing an encoded audio information on the basis of an input audio information and a computer program.[0003]Embodiments according to the invention are related an improved spectral noiseless coding, which can be used in an audio encoder or...

AI Technical Summary

Benefits of technology

[0024]In an advantageous embodiment, the arithmetic decoder is configured to set the current context state to a predetermined value in response to the detection of the predetermined condition. It has been found that this reaction is very simple to implement and still results in an adaptation of the context which provides for a good coding efficiency.

[0025]In an advantageous embodiment, the arithmetic decoder is configured to selectively omit a calculation of the current context state in dependen...

Problems solved by technology

Also, it has been found that the complexity of an audio decoder, which is often implemented in a portable consumer device, and which should therefore be cheap and of low power consumption, is dependent on the coding used for encoding the spectr...

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